Virtu, thank you for the review. As a U12 (with B1 module) owner I would like to offer some feedback. First of all, I agree with your comments regarding the design. It is true the design is somewhat lackluster for a totl product, however, I felt the build quality is good. Build quality and design are two separate issue to me. I also agree with your assessment in the area of fit.
However from your description of the ADEL technology on page one, it is apparent that you are not very well informed or familiar on the various modules of the ADEL technology available (S1, B1, and MAM) and their impact on the sound signature on U12. From your picture, it seems like you have their S1 module which is almost a closed ADEL model with very very different sound signature from the B1 module or the Mam module. Most owners of the U12 actually prefer the B1 module as it gives a much more open sounded signature which is different from the veiled description that you referred to. That is why when I first read your review, I was wondering what iem are you talking about as that is not my experiences with my U12. There are 383 pages on the Adel and U/A series of iems in the forum on the U/A series thread and the different sound signatures that each has. With the S1 module, it has the strongest bass and it at times does give an impression of a veil signature. Bass is not a weak point with U12, in fact, according to many impressions on the ADEL thread, U/A12 has the best bass.
You stated in page two "Getting into the mids, I didn’t find them very impressive for the price. Sure, given the IEM’s musicality, it continues to give you that soft and smooth feeling whole the time, but it lacks the energy you require with some genres...It would be much nicer if they could make the mids more open, energetic and airy." My U12 is much open with B1 than what you described, it has energy and details.
"Instruments don’t have a great extension and timbre. This is critical for Jazz listeners for example, for the fact that you need a natural sound with a sax for instance. With U12, it comes to yours ears like an artifical electronic recording. Maybe this has something to do with their ADEL Technology, or with the IEM’s different tonality. Either way, it’s a bit too soft and feels wrong in some cases. It’s almost like you’re sitting and listening to your music behind three veils. You want to open those veils sometimes, but you can’t. I think the guys at 64 Audio put in a great effort to make this IEM very smooth and organic, but at the same time it gives away some air and timbre. Of course, every design has trade offs. You have to decide what direction you are going and you can’t have everything at once." I think this is different from most U12 owners' experience. I find my U12 to have good details and separations.
"This thickness can bore the listener who wants a dynamic and energetic sound." the U12 is not boring. I find the mids to be intimate and involving. I can hear all the details that I want to hear.
It is unfortunate that you do not have all the modules available for review, but I wanted to point them out so readers will not mistaken your impressions to be consistent with the majority of the U/A12 owners experience.